Up to fifth-order Raman scattering of InP under nonresonant conditions

We present Raman spectra of InP measured under nonresonant conditions revealing multiphonon processes up to fifth order. Using an incident photon energy in the absorption region of the compound but far from any of its interband transitions, nonresonant multiphonon processes of order higher than two, which have not been reported so far in a zinc-blende-type semiconductor, have been observed in indium phosphide. In this way it has been possible to detect contributions not only from the longitudinal optical phonons but also from the transverse optical phonons in the higher-order peaks. We find a very good agreement between multiples of the TO- and LO-phonon frequencies at the zone center and the higher-order phonons measured in the experiments. The trend of strong intensity reductions observed when passing from first to second as well as from second to third order is not maintained when going from third to fourth, and from fourth to fifth order

Differences in the Contractile Properties of the Biceps Femoris and Semitendinosus Muscles Throughout a Season in Professional Soccer Players.

The aim of this study was to monitor seasonal changes in the mechanical and neuromuscular characteristics of the knee flexor muscles with tensiomyography, the biceps femoris (BF) and semitendinosus (ST) muscles, of 27 soccer players. All male professional soccer players (age 25 ± 4 years) were measured at the beginning of the preseason (second week) and in the competitive season (10 weeks later). The variables contraction time (Tc) and muscle displacement (Dm) showed significant differences in some muscles, and in others they indicated a tendency to change. In general, the BF improved (more explosive and better muscle tone) and the ST worsened (slower and worse muscle tone) its values during the season. The findings of this study suggest that usual daily soccer training and weekly competition might produce antagonistic changes between the knee flexor muscles.post-print452 K

Effect of an Individualised Training Programme on Hamstrings and Change Direction Based on Tensiomyography in Football Players.

The aim of this study was to analyse the effect of an individual training programme based on the tensiomyography results in the contractile properties of the knee flexor muscle with football players. Thirty-four subjects were recruited and assigned to an experimental (EG) or control group (CG). The contraction time and the muscle displacement measured by tensiomyography were assessed on two occasions: pre-time (middle of the competitive season, January) and posttime 8 weeks later. The training programme aimed to improve muscle tone and explosiveness according to the individual needs of each player. There was a significant interaction between time (assessment points) group (EG vs. CG) muscle in multivariate analysis. The findings confirmed that mechanical and neuromuscular characteristics changed over time and varied with the individual training programme (EG vs. CG) and the muscle being analysed. The 90 change of direction worsens the execution time in the control group and is maintained in the experimental group. The individual training programme, based on the tensiomyography results, showed improvements in the contractile properties in the muscles. Football coaches could use the programme to improve neuromuscular characteristics that improve performance and reduce the risk of muscle injury.post-print1285 K

“Los atentados contra la libertad de expresión y la libertad de prensa en Colombia […] muestran que la salud de la democracia anda mal”. Treinta años de una constitución hecha trizas

Colombia ocupa el puesto 130 entre 180 en la Clasificación Mundial de la Libertad de Prensa 2020, superando solamente a México, Venezuela y Honduras, en América Latina. El clima es de autocensura y violencia

Laser thermal annealing effects on single crystal gallium phosphide

We have studied the laser thermal annealing (LTA) effects on single crystal GaP. The samples have been analyzed by means of Raman spectroscopy, glancing incidence x-ray diffraction (GIRXD), and transmission electron microscopy (TEM) measurements. After LTA process, the Raman spectra of samples annealed with the highest energy density show a forbidden TO vibrational mode of GaP. This result suggests the formation of crystalline domains with a different orientation in the annealed region regarding the GaP unannealed wafer. This behavior has been corroborated by GIXRD measurements. TEM images show that the LTA produces a defective layer with disoriented crystalline domains in the surface. The depth of this defective layer increases with the energy density of LTA. The lack of crystallinity after LTA processes could be related with the high bond energy value of GaP

Continuous and Localized Mn Implantation of ZnO

We present results derived from continuous and localized 35 keV (55)Mn(+) ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature

Electrical characterization of Al/SiNx : H/n and p-In0.53Ga0.47As structures by deep-level transient spectroscopy and conductance transient techniques

We have analyzed the influence of the dielectric composition and the post deposition rapid thermal annealing (RTA) treatment on the electrical characteristics of electron-cyclotron-resonance plasma-deposited SiNx:H/n and p-In0.53Ga0.47As interfaces. The devices are characterized by means of capacitance-voltage (C-V), deep-level transient spectroscopy (DLTS) and conductance transient analyses. Our results show that a simple cleaning step of the semiconductor surface prior to insulator deposition, and a post deposition RTA process are sufficient to obtain good-quality structures, the n-type being better than the p-type. In both cases, we conclude that a dielectric composition of x = 1.50 seems to be the best choice, and that the most adequate RTA temperature is between 500 degreesC and 600 degreesC

Electrical characterization of low nitrogen content plasma deposited and rapid thermal annealed Al/SiNx:H/InP metal-insulator-semiconductor structures

The influence of the dielectric composition and post deposition rapid thermal annealing (RTA) treatments on the electrical characteristics of low nitrogen content plasma-deposited Al/SiNx:H/InP structures were analyzed. To obtain the interface state density, deep level transient spectroscopy (DLTS) measurements were carried out. We have also evaluated the insulator damage density, the so-called disorder-induced gap states (DIGS), by means of conductance transient analysis. As for the dielectric composition, both the x = 0.97 and x = 1.43 values provide interfacial state density and DIGS damage values of the same order of magnitude. In the x = 0.97 case, RTA treatments reduce the insulator damage moving it towards the interface. In the x = 1.43 case this behavior is only observed for RTA temperatures lower than 500 degreesC. So, moderate temperature (C) RTA treatments improve DIGS damage. This is an important result in terms of fabricating bi-layered metal-insulator-semiconductor (MIS) structures that not only have good-quality interfaces, but also good dielectric properties

C-V, DLTS and conductance transient characterization of SiNx:H/InP interface improved by N-2 remote plasma cleaning of the InP surface

Electrical characterization of Al/SiNx:H/InP structures shows that ECR nitrogen plasma cleaning of InP surfaces gives rise to a noticeable improvement in the interface quality, whereas insulator and semiconductor bulk properties are maintained at a level sufficient to be used as the gate dielectric in MIS devices. Nitrogen plasma exposure was carried out just before the SiNx plasma deposition without vacuum breaking. To obtain interface state density and to detect deep levels in the semiconductor bulk, deep level transient spectroscopy (DLTS) measurements were carried out. We have also evaluated the insulator damage density, the so-called disorder-induced gap states (DIGS), by means of conductance transient analysis. Our results show that the plasma exposure in N-2 atmospheres is a valuable and simple surface conditioning method

Comparison of Raman-scattering and Shubnikov-de Haas measurements to determine charge density in doped semiconductors

We have verified the accuracy of free-charge determinations from Raman scattering in doped semiconductors by comparing the results obtained from phonon-plasmon coupled-mode line-shape fits with the charge-density values extracted from the analysis of the Shubnikov-de Haas oscillations. The experiments were carried out on n-InP layers, and conduction band nonparabolicity was included both in the Lindhard-Mermin model used to fit the Raman spectra and in the Shubnikov-de Haas analysis. We find a very good agreement between Raman and magnetotransport results, which confirms the reliability of the charge-density determination from Raman-scattering measurements when the line-shape analysis is carried out using the Lindhard-Mermin model